The long range goal of this project is to determine the structural characteristics of proteins which have stimulatory effects upon eosinophilic leukocytes. I have isolated a protein from metacestodes of Taenia taeniaeformis (ECF-Tt) which has specific chemotactic activity toward equine and murine eosinophils. This ECF-Tt is immunologically cross-reactive with the fusion protein TA23, identified from a cDNA library of 28 day metacestodes. After confirming the identity between ECF-Tt and TA23, I will determine the DNA sequence and, thereby, the amino acid sequence of recombinant ECF-Tt. I will then quantitate the ability of native and recombinant ECF-Tt to stimulate selected eosinophil functions, including migration, secretion, and proliferation. I will also test the ability of ECF-Tt to induce the production of lymphokines which stimulate eosinophil migration and differentiation. The results of these experiments will lay the foundation for future studies including isolation and characterization of an eosinophil chemotactic factor.